The invention relates generally to the field of combining fluids. More specifically, the invention relates to apparatus and methods for uniformly mixing fluid phases entrained in a porous medium.
The mixing of fluids is frequently needed to perform chemical reactions. Most chemical reactions require a controlled and homogeneous mixing of reagents.
A conventional means of mixing two or more miscible liquids is mechanical manipulation to stir and exploit fluidic forces to produce localized regions corresponding to relatively high fluid flow rates. The flow rates operate to produce localized turbulent forces within the fluid field. The turbulence provides a contact surface between the liquids such that diffusion of the fluid components into each other produces a homogeneous mixture.
Mixing also includes homogeneous compositions of immiscible fluids such as oil and air, typically used in oil jet pumps for gear lubrication. Oil and air are not miscible in a chemical sense, but may be combined in a mechanical sense. The term frequently used for mixing immiscible substances is homogenization.
Ultrasonic mixers use piezoelectric transducers to generate vibrations. High power output may be required to maintain the desired amplitude and intensity under conditions of increased load such as high viscosity or immiscibility.
When a porous medium, such as a polymer membrane, is used to contain reagents, equilibrium diffusion is problematic. While ultrasonic mixers have been employed to provide bulk mixing of liquid and gas, they have not been successfully employed for porous materials. Typically, the only known approach for mixing intensification inside porous bodies has been mechanical manipulation which might not be feasible or desirable in every case.
What is desired is a controlled acceleration of mixing in porous media. This would result in smaller physical component packaging for synthesizing units housing porous media such as those used for chemical reactors, fuel cells, and the like.